Considered are the issues of landslide hazard on land and in the waters of the World Ocean in relation to the operation of oil and gas facilities, including oil and gas production fields and subsea trunk pipelines. Specific examples are given concerning the loss of oil and gas production platforms and the pipelines destruction during landslides of bottom sediments in the Gulf of Mexico caused by the hurricanes in 1969 and 2004.
It is established that the bottom of the continental slope of the Black and Azov Seas and adjacent land areas are subject to extensive landslide processes. As a result of the bottom slope angles calculations using the latest bathymetric data from GEBCO and the distribution of the underwater canyons with weakly consolidated sediments, the cartographic scheme of the risk of landslides in the Azov-Black Sea basin was drawn up. The high level of landslide threats at the bottom slope angles above 0.5° is substantiated for approximately 27.4 % of the Black Sea area. It is shown that in the Black Sea a number of fields and long sections of the underwater pipelines are located in the zones of increased risk of landslides.
It is substantiated that due to climate warming with global sea transgression, the level of landslide threat increases. The occurrence of landslides is facilitated by permanent gas release, which dilutes the bottom sediments. The new underwater landslide mechanism caused by gas-dynamic processes in the forms of massive gas blowouts with formation of large craters —pockmarks is formulated in the article. At the same time, the crater is a weakened zone in the array of weakly consolidated bottom sediments and gives rise to landslide processes inside and around the crater. In addition, a powerful gas outburst generates elastic vibrations (seismic waves), which also contribute to landslides.
It is suggested to develop the initiated studies of landslide hazards in other Russian seas — primarily the Arctic shelf, the Sea of Okhotsk, and the Caspian Sea, where offshore oil and gas fields are already operating.